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In order to specify insulation correctly however, the specifier needs to understand the reasons why it works, and apply the correct technology to any given construction detail. In understanding more fully the processes that make insulationwork, and indeed the factors that stop it from working, specifiers will be in a far stronger position to specify the correct material for the correct application.

Any object whose temperature is higher than the surfaces that surround it will lose energy as a net radiant exchange. Radiant heat can only travel in straight lines. Introduce a solid object between points A and B, and they will no longer directly exchange radiant heat. Radiation is the only heat transfer mechanism that crosses vacuums.

Convection is the transfer of energy via fluids (gases and liquids). It is this method that plays the greatest role in the liberation and transfer of heat in buildings. The most common propagation of this effect is from solid to gas, i.e. object to air, and then back again, typically as the air meets with the external building fabric.

The process is actually initiated by an energy transfer due to conduction, and is complicated by the level of water vapour that is supported by the air. The water molecules store heat given to them through conduction from warm surfaces. The water vapour and the air cannot be separated as gases. They will only part company when the saturated vapour pressure is reached, i.e. the quantity of water (albeit in vapour form) exceeds the level of heat available to maintain it as a gas (vapour), and therefore it condenses.

If air could be kept still and dry it would perform as a highly efficient insulant. However, if air is heated, its molecular structure expands and becomes less dense relative to the air surrounding it, and so rises. As it progresses further from the heat source, it begins to cool. The molecules contract and increase in density and sink back down. Air molecules are in a constant state of flux, dependent on the ambient temperature, and interference from any point, or background heat sources.

The graphic below shows a sectional core image of a typical glass wool product overlaid with a representation of the millions upon millions (per square metre) of 'open cell' air pockets that are created during manufacture. At the same time as the manufacturing process forces air into the core of the glass fibres, a previously introduced binding agent is activated to form a matrix locking the composition together. This produces the 'spring loading' that is associated with mineral wool insulation, allowing it to regain its shape and thickness after compression.

The open cell nature of the matrix will allow air migration through its core, but the route is tortuous and so heat loss due to convection is minimal. The principle in operation is the formation of such small air pockets that air movement is brought to a virtual, but not complete, stop.

Dry air is a good insulation gas. So with open cell products, if contamination of the core air by water vapour can be prevented (using vapour control barriers), the ultra small air pockets will significantly limit air movement.

Closed cell insulants include products such as extruded polystyrene and chemical foam-boards. Closed cell technology utilises the controlled introduction of gases (blowing agents) during manufacture that form a much more dense matrix of individual cells than glass wool or EPS. The cells are formed as bubbles of the gas whose thermal conductivity is significantly less than that of air. Combine this with the inability of water vapour to readily contaminate the cells, and this provides for a significantly higher performing insulant. (NB: The matrix of some chemical foam insulants may be susceptible to break-down over time by the presence of water, or water vapour.)

The cell walls are extremely thin which limits conduction, but are gas tight. The dense cellular composition further limits the potential for gas movement, as it may only move within the confines of its containing cell, and not between cells. So as with open cell materials, the process of heat transfer from warm to cool sides is affected by a combination of conduction via the cell walls and limited convection via the cell gas.

The material's efficiency is very high and effective over the area of an unbroken board, but is significantly reduced by poor workmanship in board cutting and jointing.

To this end specifiers may take note of the implementation of Green Deal assessments. The diktat here is to adhere to the 'golden rule' that the cost of the energy saving measures proposed must not exceed the projected savings made by the resulting use of less energy. In practice, in order to make sure of this, Green Deal Assessors (GDAs) are adopting a very conservative line on projected savings, and projected savings involving insulation use calculations at 75% of the manufacturer's performancedata.

The faster the air movement over a heat source, the faster the heat transfer occurs. The presence of water droplets will act as an accelerant to this process, although control over water vapour saturation will usually need to be exercised to avoid problems caused by condensation.

Addressing the cellular construction of dedicated insulationmaterials, the intrinsic aim is to prevent the movement of gases within the insulation core matrix, in doing so the loss of heat consequential to that movement will also be reduced.

There are open cell foamed products available that due to their core matrix composition have a higher thermal conductivity than their closed cell cousins, but have advantages with greater flexibility to accommodate building movement, and any deterioration of cell walls will not result in the liberation of the gas content.

There are better performing technologies on the market with 'aerogels' and 'evacuated panels', but performance is reliant upon the same principles of heat transfer, and for the time being has a limited specification niche, remaining largely cost prohibitive for the vast majority of applications.

Comments

Thermal insulation material - works on a different basis than well-known heat insulating materials - polystyrene or mineral fibre. Its development is a result of a request for insulating heat which is transmitted by heat emission. It has been found out that up to 90 % of heat is supplied in summer and up to 50 - 70 percent of energy is transmitted this way in winter. The result of these facts is that insulation which keeps the heat inside a room during winter, can save considerable financial costs on heating. It is possible to sum up that heat insulation is able to lower lost of heat even the layer is only 0.8 up to 1 mm thick. This way the temperature inside a rooms goes up very fast. In summer walls treated by this matter slow overheating down.

Thermal insulation material is an ideal material for inner heat insulation of walls in construction, mainly of concrete buildings, thermal bridges, parts of walls behind heating elements, where due to condensation, mould can appear and for all spaces which are inadequately heat insulated and where it is required to increase the temperature in a room by increasing the temperature of walls and where savings of energy is required in combination with controlled thermoregulation of heating systems. Tests which have been carried out but more importantly the experiences of users proved that in relation to the type of properties and to the heating system it is possible to save 25% or more on heating expenses.

Thermal insulation material can be applied on interior surfaces, such as lime cement plaster, concrete, plaster, plasterboard, prefabricated materials, wood and its side product, metal surfaces, glass and many others and everywhere where it is necessary to achieve insulation and it is not possible or suitable to use other materials and application procedure ( for example properties with valuable facades, where it is not possible to apply common materials).

Thermal insulation material is also suitable as an interior heat insulation in industrial halls and as an insulation of hot or cold water pipelines, it can be used as a heat insulation in places which are not regularly heated such as cottages, holiday homes, cabins, garages and other similar places, where it is necessary to increase temperature very fast and at the same time to prevent the effect of cold walls. It can be applied in floor heating, this way the building height can be lowered.

Thermal insulation material offers more effective system of heating and energy saving mainly in periodically or short term heated places such as cottages, cabins, offices, catering ( here lower predisposition to unwanted changes in coloured surface due to nicotine is appreciated ), hotels, hospitals and also flats where during absence of people or due to accidental use of the space, it is possible to considerably lower the temperature but also in very short time to increase this temperature without any risks of heating the walls first and then stabilising the room temperature. "Hot head and cold feet" effect - who have not faced such situation in cold winter months?

Thermal insulation material will take care for the even distribution of heat in a room.

Thermal insulation material is excellent material for achieving an anti-condensation effect. Occurrence of cold areas on interior walls mainly in corners can cause condensation of room humidity and subsequent occurrence of mould. The idea behind using thermal insulation material is to distinctively decrease dispositions for creating condensation with the existence of microscopical air spaces in painted surfaces and this way decrease the possibility of mould occurrence. This characteristic allows. Thermal insulation material, to be used in all areas with high humidity and insufficient ventilation: in bathrooms, kitchens, in factories processing food, etc. One of the advantages is the fact that the walls are warm to touch, they have perfect permeability and offer better acoustics.

Thermal insulation material is supplied in white colour with possibility of colour toning with water soluble colours. The surface of the coating is possible to grind or paint after setting. The coating does not smell, it is not deleterious and during setting is does not transpire any chemical substances. The final coating is permeable, washable and it improves the acoustics of a room. The value of diffused resistance for water steam admittance (p =30) is only slightly higher than with ordinary lime-cast coat. Diffusion equivalent of the thickness of an air layer is Sd< 0.7m. Gripping to the base is 1MPa. Where applying coat from interior thermal bridges are broken and it prevents condensation of water steam on walls, whereby it prevents growth of fungus and it keeps anti-allergic environment.

Thermal insulation material is applied to firm, dry and clean surface. When using on the existing coating the surface must be degreased and treated with penetration coating. Should there be more than one coat on the surface it must be removed. Uneven surfaces and cracks need to be smoothed by a spattle . Prior to application to a non-absorbent base connecting bridge must be created.

Thermal insulation material is applied to prepared surfaces with a spattle, by spraying or by coating. According to the type of coating Thermal insulation material is diluted in given proportions. Caution is necessary when stirring the substance, it is stirred with a slow speed in order not to damage the structure of used filler. When applying with a spray-gun the pressure is to be on a value of 5 bar (atm.) - the value of a manometer. Higher value could damage the structure of used filler and cause a loss of stated characteristics.

Thermal insulation material after application it is resistant to from -40°C to +150°C without the loss of its stated qualities. When applying in interior, the problem of painting is also solved. Subsequent decorations can be applied onto the insulation already carried out without any limitations.